Steering and braking equipment assist a driver of a vehicle to direct and brake the vehicle in a controlled, predictable manner. In conventional steering assemblies, the operator controls the direction of the vehicle with the aid of a steering wheel. This wheel is mechanically connected, usually through a gear assembly to the roadwheels. In conventional braking systems, the operator controls the deceleration of the vehicle by applying a force to a pedal, displacing hydraulic fluid to transmit the force to a piston, which in turn applies force to a braking surface to slow the vehicle. To aid the operator, many steering and braking systems utilize an auxiliary system to generate additional force that is transmitted to a steering gear or braking assembly. The additional force reduces the effort required by the operator providing an xe2x80x9cassistxe2x80x9d or boost. Typically, this auxiliary force is generated by either a hydraulic drive or an electric motor.
In the case of steering systems, the steering wheel is mechanically connected directly to the roadwheels, the resulting mechanical assembly that provides the connection can be quite complicated and expensive to produce. Likewise, for braking systems, the configuration of hydraulic systems for braking may be complex, can leak, and are subject to contamination.
One advantage in having a direct connection is that the operator receives tactile feedback through the mechanical connections to the actuated component. For example, if the vehicle changes directions while it is moving, the operator will feel resistance in the steering wheel. However, such systems inherently include fabrication and implementation limitations and lack the capability to dynamically tailor system response characteristics to accommodate a variety of environmental conditions
Steer-By-Wire, Brake-By-Wire, or Drive-By-Wire systems overcome some of these limitations by allowing for electronic control of braking and steering of a vehicle. Such systems can control the steering and braking functions of a vehicle using a control device, such as a steering wheel and brake pedal or joystick. Typically, these systems have more than one communication channel for communicating signals from the control device to the steering and braking motors such that, when that communication channel experiences an error, the entire system is not inoperable. However, these systems may not provide the best utilization of sensors, components, actuators, or controllers.
Control systems with redundant communications networks are typically accomplished using two different families of device controllers, wherein each family (e.g., braking and steering) of device controllers operates independently on two separate networks. These redundant systems require a significant amount of hardware, which is difficult and expensive to package in a vehicle with a control-by-wire system.
Control-by-wire generally refers to control of vehicular systems where the operator input and associated actuating device, such as for example a brake caliper or steering actuator, are connected by wire or wireless connection rather than a physical apparatus. Rather than such physical apparatus communicating a force, motion, or other actuating means directly to the actuating device, this connection, communicates a command signal to the actuating device, corresponding to the desired response of the actuating device. Integrated control-by-wire system and system architecture is also referred to as xe2x80x9cX-by-Wirexe2x80x9d to identify that more than one system or type of system is controlled xe2x80x9cby wirexe2x80x9d.
Therefore, is it considered advantageous to identify an X-by-Wire control system and architecture that provides customizable system functional characteristics and optimizes controller and component utilization.
A control-by-wire control system comprising a plurality of control device(s), each control device responsive to, and configured to receive a control signal. Also included in the control-by-wire control system is a plurality of sensors wherein certain sensors are coupled to particular control devices. The sensors, each sense a parameter of the system and generate various sensor signals in response. A plurality of control modules is also included in control-by-wire control system. Each control module is interfaced to at least one of the control devices and is adapted to receive at least one or more sensor signals. The control modules also generate control signals for communication to the control devices. A communication interface of at least two communication networks provides communications among various control modules. The control-by-wire control system is architected to ensure that inoperability of any one of the control devices, control modules, sensor signals, or communication networks, will not result in loss of functional capability of the control-by-wire system.